Medtronic's Most Popular Defibrillator Lead Faulty?

Could Medtronic's very popular downsized defibrillator lead, the Sprint Fidelis Model 6949, have problems? We were notified a while ago about a "clustering" of fractures with this lead design, but it was thought that the problem occurred if the distal tip became acutely bent during the implant process or the lead was secured improperly at the chest area in a "Dear Doctor" letter. We've been following this lead carefully.

In reviewing our database of implants, as of today, we have 264 patients have implanted and follow with the Sprint Fidelis lead (Model 6949) since 2005. We have three different implanting physicians at our institution. Number of fractures, insulation breaks, deaths or other
problems? Zero.

But now, according to this news article from the Star Tribune, a death in a patient with this lead is being investigated. This was confirmed in a separate piece from theheart.org:

According to reporter Janet Moore, 169 000 Sprint Fidelis leads have been used since the US Food and Drug Administration approved them in September 2004. Doctors, she writes, prefer it because it is thin and nimble, and the company says the overall fracture rate is "extremely low." Although Medtronic informed the FDA about the lead fractures, the letter was not considered an official advisory, nor has the FDA recalled the leads.

"Unlike its February 2005 defibrillator recall, Medtronic did not issue a news release, and a product performance report on its website lists no advisories associated with Sprint Fidelis leads," writes Moore. "Patients would likely hear of potential problems through their doctors."

...

Ms Moore noted that a study published in the journal Heart Rhythm by Dr Robert Hauser (Minnesota Heart Institute Foundation, Minneapolis, MN) found that six Sprint Fidelis leads failed of the 592 implanted at his institution between September 2004 and February 2007. An additional analysis of FDA data revealed 679 reports for the leads during a 30-month period, and that Medtronic found 77 of 125 returned leads defective, mainly with tears. Of seven deaths, one was attributed to shocks, but no details on the patient were provided, reports the Star Tribune.

Based on these data, Hauser concluded "that the Sprint Fidelis leads appear prone to early failure, probably because they are thinner, and perhaps less robust," writes Moore. He did, however, praise Medtronic, noting that the company was candid and forthcoming with all requests for information.

But what Ms. Moore failed to mention was the excellent accompanying editorial by Dr. Bruce L Wilkoff, MD from the Cleveland Clinic and Case Western Reserve University (Heart Rhythm, Vol 4, No. 7, July 2007) which raises the question about the role that the implanting physician might have in creating an elevated complication rate. Certainly this has been called into qeustion with drug eluting stent failures as well (inadeuquate stent deployment). Teasing out the problems with leads caused by implant technique versus the lead itself, or even patient variables (size, anatomic variationsm etc.), is a significant challenge for device makers.

To paraphrase Dr. Wilkoff, once a decision is made to communicate with the physician and public about lead failure findings, great care care must be exercised to define the problem. Scarey terms like "lead tears" as in Ms. Moore's article should be avoided, since even those in the field are confused by her interpretation of the issues. Secondly, data should be actively collected regarding failures and implants, so that real deviations from norms can be quickly identified and the magnitude of the problem defined. Finally, there should be active resistence to lump failure types together and jump to conclusions. There are three different failures noted in the analysis discussed in Dr. Hauser's article, and Dr. Wilcoff wisely questions if these failure mechanisms are related. To exclude any one of the failure mechanisms (lead design, operator technique, and patient variables) as a potential cause might lead the lay press to jump to conclusions - after all, it makes good reading.

-Wes

Disclosure: I am on the speakers bureau for Medtronic and Boston Scientific.